JPS61243910A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To make possible the depth control with high accuracy without receiv ing the influence of the difference in the accuracy of pattern formation by connecting two conductor patterns with a conductive magnetic layer via through- holes formed thereon. CONSTITUTION:The pattern of conductor layers 16, 17 and insulating layers 2a, 2b are formed on a substrate 1 which acts as a lower magnetic core and thereafter the conductive magnetic layer 20 to short circuit both conductor layers 16, 17 is formed via through-holes 18, 19 formed by removing part of the insulating layer 2, by which a monitor 15 is completed. The arrival of the polishing at the prescribed position can be recognized from the abrupt change in the electric resistance between the conductor layers 16 and 17 when the thin film magnetic head provided with such monitor 15 is polished. The prescribed depth length is thereby obtd. The influence of the pattern shifting of the monitor and the difference in the accuracy of the pattern formation is thus eliminated and the depth control with high accuracy is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin-film magnetic head, and more particularly to one equipped with a depth control monitor for controlling depth processing of a surface in contact with a magnetic recording medium.

[Conventional technology]

In general, a thin film magnetic head has a configuration as shown in Figure 9, in which (1) is a ferromagnetic substrate constituting the lower magnetic core, (2) is an insulating layer, and (3) is a conductor. layer,
1.4) is the upper magnetic layer constituting the upper magnetic core,
The conductor layer (3) is interlinked with a magnetic loop made of the substrate (1) and the magnetic layer (4), and the insulating layer (2)
It is electrically insulated from K.

This thin film magnetic head is formed through the steps shown in FIG. 10, for example. That is, (1) First,
As shown in Figure (a), a ferromagnetic substrate such as ferrite (
1] A first insulating layer (2a) made of an S io2 film with a film thickness of 5 KA is formed on the insulating layer (2a), as shown in (10) in the same figure.
A Ti film (adhesion) with a film thickness of 0.5 KA is formed on top and bottom, respectively, (11D) Furthermore, as shown in the same figure (C), a film is formed on 5i with thickness 7KA
A second insulating layer (2b) made of an N2 film is formed, and a voltage of 6 V is then applied to the upper and lower magnetic core connection parts, that is, at two positions sandwiching the conductor layer (3), as shown in (d) of the same figure. Both insulating layers (2a) and (2b) are removed to form through holes (5a) and (5b). Second insulating layer (2b) containing holes (5a)
A gap forming layer (6) made of a SiO2 film with a film thickness of 5KA is formed on the upper surface of the film, and as shown in FIG.
The upper magnetic layer 1.4) made of a Ni-Fe (permalloy) film has through holes (
5a) and (5b), and (vii) as shown in FIG.
．． 4) and the top surface of the gap forming layer (6) with a film thickness of 30K.
A protective layer (7) made of the SiO+ film of A is formed.

Note that these films are formed using thin film forming techniques such as vacuum evaporation and sputtering, and patterning involves covering the necessary areas with photoresist and removing unnecessary parts of the film by irradiating with inert gas or reactive gas. It is carried out by

After the thin film magnetic head obtained in this way is subjected to a cutting process, a protective film (7
) A protective plate (9) is adhered thereon via an adhesive (8), and the surface facing the magnetic recording medium is polished to finish.

By the way, in the above-mentioned polishing process, since the distance between the contact surface α1 and the depth end, that is, the depth length t, is set to 5 to 10 μm, depth control on the order of microns is required.

For this reason, conventionally, in the thin film forming process of thin film magnetic heads, a depth control monitor for measuring the depth length has been created integrally with the substrate, and the amount of polishing has been controlled by measuring the depth length using this monitor. Yes.

For example, in Japanese Patent Application Laid-open No. 56-29832,
@12 As shown in Figure 12, a large number of comb-shaped teeth C11) are provided on the substrate (1) constituting the lower magnetic core of the thin film magnetic head with a first insulating layer (2a) interposed therebetween. It is described that depth control monitors 03 having different lengths of teeth αυ are provided, and the depth is controlled by measuring the amount of polishing based on the number of teeth aυ visible from the polished surface during the polishing process.

However, with such an optical monitor, it is necessary to measure the amount of polishing by stopping polishing and observing the polished surface with a microscope, which has the drawback of significantly increasing the number of man-hours.

Therefore, there are electric monitors that can measure the amount of polishing without stopping polishing. For example, the depth control monitor disclosed in Japanese Patent Application Laid-open No. 57-94923 is as shown in FIG. On the substrate (1), thin film resistive films α3 parallel to the polishing surface are arranged at predetermined intervals in the direction of polishing progress, and each resistive film α3 is connected in parallel with a terminal conductor layer α.

Therefore, as the polishing progresses, each resistive film α3 is sequentially polished and removed, so that the electrical resistance value of the resistive circuit formed by each resistive film α3 changes as shown in FIG. 14 according to the amount of polishing. The amount of polishing is measured by the change in resistance value.

[Problem that the invention seeks to solve]

However, with the above-mentioned electrical monitor, no change in resistance value can be obtained during polishing between each resistive film 03, and there is a region in which the amount of polishing cannot be measured.Moreover, each resistive film α
During the polishing step No. 3, the resistance value changes gradually, making it difficult to detect the position of the resistive film breakage and making it difficult to measure the amount of polishing, that is, to control the depth.

On the other hand, the thin film magnetic head is obtained by the forming process explained in FIG. 10, but the depth end of this magnetic head is
The insulating layer (2) and its pattern, that is, the through-hole (5a): are determined by the insulating layer (2) and its pattern, and as this is a separate process from the formation of the depth control monitor, pattern deviation between the monitor and the insulating non-pattern, pattern formation accuracy The difference between the two results in a depth measurement error, which impedes highly accurate depth control.

Therefore, it is an object of the present invention to obtain a thin film magnetic head equipped with an electric depth control monitor that clarifies the measurement of the amount of polishing and that does not cause pattern deviation or difference in pattern formation accuracy from the depth end forming process. is a technical issue.

[Failure to solve the problem]

In this invention, a conductor layer is formed on the lower magnetic core via a first insulating layer, a second insulating layer is formed to cover the conductor layer, and souffle holes for determining the depth end are formed in both the insulating layers. In the thin film magnetic head, an upper magnetic core is formed opposite to the lower magnetic core of the through hole via a gap forming layer, and the conductor layer is linked to a magnetic loop formed by both the magnetic cores. A conductor that electrically connects the two conductor patterns formed on the lower magnetic core and the side conductor pattern through the through holes on the conductor patterns formed in both the insulating layers when the through holes are formed. The device is characterized by having a magnetic layer and a depth control monitor.

[Effect]

Therefore, in the thin film magnetic head of the present invention configured as described above, when the surface in contact with the magnetic recording medium is polished, a part of the circuit formed by the magnetic layer of the depth control monitor is removed and disconnected, so that the polishing position is changed. This disconnection position is recognized and measured by forming a through hole in the same insulating layer that determines the depth end, where the upper magnetic core is formed at the same time as the through hole facing the lower magnetic core. There is no pattern deviation or difference in pattern formation accuracy from the depth end formation process.
Accurate depth control will be performed.

〔Example〕

Next, the present invention will be explained in detail with reference to FIGS. 1 to 8 showing embodiments thereof. Note that in these drawings, the same symbols as above indicate the same or corresponding items.

(Embodiment @1) First, FIGS. 1 to 3 showing the first embodiment will be described.

The one shown in Figure 1 is a ferromagnetic substrate (
1), an upper magnetic layer (4) that becomes the upper magnetic core that forms a magnetic loop with the substrate (υ), and an insulating layer (2) that is electrically insulated from the VC with respect to the substrate (1) and the magnetic layer (4). A depth control monitor μ formed simultaneously on a magnetic head element consisting of a conductor layer (3) interlinked with a magnetic loop.
s, and is formed by the forming process shown in FIG.

In other words, the formation process of this monitor +1!19 is the 10th
To explain the process of forming the magnetic head element shown in the figure (steps (1) to (Vi+) described in the conventional technique), (5) First, as shown in FIG. 2(a), Prior to creating the magnetic head element, a film with a thickness of 0 is applied on the top and bottom of the substrate (1).
, C of A with a film thickness of 10 having a Ti film (adhesive layer) of 5KA
Two conductor layers αQ and η made of U film are patterned.

(G) Next, as shown in FIG. 2(b), as shown in FIG.
The substrate (1) and both trench layers oQ are formed by the steps a), (b) and (C).

'J'i) on @1. Second insulating layers (2a) and (2b) are formed.

(q Furthermore, as shown in Figure 3 (C), @io diagram (
Insulating layer (2a) of the upper and lower magnetic core connection parts in step d), (
2b), i.e. through-holes (5a), (5b
) is simultaneously formed, an insulating layer (2
a).

A part of (2b) is removed to form a through hole (to) α9. When removing the insulating layers (2a) and (2b), not only the Cu films of both trench layers ae and αη but also the substrate (1
) It is necessary to use a method that does not attack the ferrite. For example, etching using CF4 plasma is effective. Here, in the through-hole α which is closer to the polished surface, the edge opposite to the polished surface and the depth end position (the edge opposite to the polished surface of the through-hole (5a)) are polished. Redundancy is set so that the distance in the direction is a predetermined depth length.

Next, in the step shown in Figure 10 (e), that is, the gap forming layer (6) step, mask vapor deposition 5 is performed to form a film to prevent the gap forming layer (6) from being formed on a part of the monitor. .

0 Then, as shown in Figure 3(d), @lO diagram < f
), a Ni-F film with a thickness of 70 KA is made to short-circuit both groove layers Ql and 071 via both through holes (to) and α9.
A conductive magnetic layer consisting of e-film is formed, and a monitor QFJ is formed.
complete.

Therefore, when a thin film magnetic head equipped with such a monitor/JG is polished, the electrical resistance value between both groove layers Q* and Q changes as shown in Figure @3 during the polishing process, and the abrupt change occurs. It is recognized that the polishing has reached the position indicated by the one-dot chain line in FIG. 1 based on the resistance value change, and it can be seen that the predetermined depth length has been obtained.

The position of this one-dot chain line is determined by the pattern of the insulating layers (2a) and (2b), that is, the through hole 01, and this also determines the depth end of the insulating layer Jl (2a).
, (2b), the same film and the same etching are used, so the relative positional deviation between this position and the depth end can be suppressed to within 5 μm (accuracy of photomask production).

Here, as the polishing approaches the position indicated by the dashed-dotted line, the magnetic layer - is gradually polished, and the new area of the magnetic layer (e) that forms part of the electric circuit becomes smaller, but the length of this part is Insulating layer (
2a), (2b) (7) Because it is extremely short and corresponds to the film thickness (1 to 2 um), the overall resistance change is kept small; The change in resistance value when the wire is disconnected can be easily identified.

For example, set the width of through hole a9 parallel to the polished surface to 4μ.
m9 The total thickness of both insulating layers (2a) and (2b) is 2 μm.
If the specific resistance of the magnetic layer is 20 .mu..OMEGA.cm, then when the polishing progresses to 0.5 .mu.m just before the dashed line in FIG. It is extremely small, within 2Ω.

(Second Embodiment) Next, FIGS. 4 to 8 showing a second embodiment will be described.

These drawings show a depth control monitor in which the resistance value changes stepwise depending on the amount of polishing of the surface in contact with the magnetic recording medium.
9 is shown, and its formation process is shown at @4.
This will be explained with reference to FIGS.

First, as shown in Figure @4, a gap forming layer (6) made of an At20s film with a film thickness of 5 KA is formed on a ferromagnetic substrate (1) that will become the lower magnetic core, and a film with a film thickness of IK^ is formed on it.

3 pieces (1) made of permalloy film with a width of 4 μm and a length of 500 μm: 1st, 2nd, and 3rd resistor 1 for -9-
[(21a), (21b), and (21C) are formed side by side at intervals of 10 μm in the direction perpendicular to the polished surface. moreover,
Gap forming layer (6) and each resistive film (21a) =
(2l b) e (21c) Film thickness 3 on the top surface
After forming the first insulating layer (2a) made of a KA SiOz film, a conductor layer (3) made of a Cu film with a thickness of 10 KA and a Ti film (adhesive layer) with a thickness of 0 and 5 KA on the upper and lower sides, and a monitor layer are formed. Two conductor layers αQ and 1η are formed simultaneously.

Next, as shown in FIG. 5, after forming a second insulating layer (2b) made of a SiO2 film with a thickness of 7KA on the top surface of the first insulating layer (2a) and each conductor layer (3), Qf9, ffη. , the insulating layers (2a) and (2b) are patterned. That is, the insulating layer (2a
), (2b), conductor layer 0Q, insulating layer (2a) on αη,
(2b) and each resistive film (21a), (21b), (2
The insulating layers (2a) and (2b) at both ends of 1C) are removed by the same etching process, and the through-holes (5a) and (5b) of the upper and lower magnetic core connection parts, respectively, and the conductor [1tQe, '1
17) Upper (7) SuJl/-Ho71/agJ#Q
lb and resistive film (21a), (21b), (21C)
Form the through-hole slope and slope at both ends.

Here, as shown in FIG. 5(a)'IC, the resistive film (2
1a), (21b), and (2IC), the edge on the opposite side to the polished surface is connected to the edge of the through hole (5a) that determines the depth end of each resistive film. (21a), (21b), and (21c) are formed in a step-like manner with intervals dx, d2, and da, and the through-hole slopes and the interval between each resistive film (21
a L (21b), (21c) every yc tl, t2.
ta ic naru, k u setting, for example, t
l = 200μm, z2 = 73 = -4QQ7z
It is m.

Furthermore, as shown in Figure @6, there is a through hole (5b) on one side of the upper and lower magnetic core connection parts, that is, on the opposite side to the polished surface.
[After patterning and removing the gap forming layer (6), the through hole (5a) of the upper and lower magnetic core connection parts is formed.
, (5b) and between the through holes (to) in the monitor part, between the parts, and between the through holes α9° (1), respectively, the upper magnetic layer 14) of the upper magnetic core made of a Ni-Fe film with a film thickness of 70 KA; Magnetic layer (20a).

(20b), connects the substrate (1) and the upper magnetic layer (4) to form a magnetic loop interlinked with the conductor layer (3), and also connects the magnetic layer between both groove layers Qf9 and ff9. (20a), 1st°, 2nd, 3rd resistance film (21a), (
21b), (2IC) and a magnetic layer ('20b) to constitute a depth control monitor/IQ.

After that, a SiO2 film with a thickness of 30 KA was applied to the entire surface of the substrate (1).
A protective layer (7) consisting of a film is formed.

Therefore, in the monitor 〇〇 as described above, a magnetic layer (20a L (20b)
via the 1st. Second. Third resistance film (21a), (21b
) and (21c) are connected in parallel, and at this time, the magnetic layers (20a) and (20b) have a large film thickness and the conductivity of the Cu that constitutes them is high, so their electrical resistance value is small. , Therefore, as shown in Figure @7, @1.
Second and third resistive films (21a), (21b), (21
c) Resistance due to vC (Ra), (R,, b), (Rc)
A parallel circuit will be constructed.

Here, assuming that the specific resistance of permalloy constituting the resistive films (21a), (21b), and (21c) is 20 μΩcm, then each resistive film (21a), (21b), and (21c) cn
Dimensions zt, t2. Resistance due to ts (Ra) * (R
bL(Rc) c') Resistance, resistance value, 100Ω,
200Ω, 200Ω.

In the thin film magnetic head constructed as described above and equipped with the monitor αi, the depth lengths are changed to dx, d2, . When it comes to daVc,
A resistive film (21a) connects both conductor layers aQ and αη.
), (21b), and (21c) are sequentially disconnected, and as shown in Figure @8, the conductor layers α*, 't'? ) is 5
It changes discontinuously from 0Ω to 100Ω, from 100Ω to 200Ω, and from 200Ω to (1).

In addition, although the example shows the case where the lower magnetic core is made of a ferromagnetic substrate (1), the present invention can also be carried out in the same way even when the lower magnetic core is formed of a magnetic film on a non-magnetic substrate. Of course.

In addition, in the case of the monitor* and aj, the connection part that is removed by polishing and disconnected is not on the surface of the substrate (1) but on the vertically laminated part of the through hole (a), so the track of the magnetic head is The area occupied in the width direction becomes extremely small, and therefore, it becomes easy to install a plurality of monitors of this type in line in the track width direction, and the area where depth detection is impossible can be made smaller.

〔Effect of the invention〕

As described above, according to the thin film magnetic head of the present invention, a discontinuous change in resistance value is obtained between the conductor patterns of the depth control monitor as the recording medium pair 71 is polished. It is possible to clearly identify the depth length, and since the circuit cutting point of the monitor is formed in the same process as the insulating layer pattern that determines the depth end, there is no difference in the monitor's one-f turn deviation or pattern formation accuracy. This completely eliminates the effects of

[Brief explanation of drawings]

1 to 8 show embodiments of the thin film magnetic head of the present invention, and FIGS. 1 to 3 show the first embodiment,
Figures 1 (a) and (b) are a plan view and a cross-sectional view of the depth control monitor, Figures 2 (a) to (d) are cross-sectional views showing the process of forming the monitor, and Figure @3 is the polishing of the monitor. Characteristic diagrams of electrical resistance value versus quantity, Figures 4 to 8 show the second embodiment, Figure @4, Figure @5 and Figure 6 respectively show the formation process of a magnetic head with a monitor,
Each (a) is a plan view, each (b) and each (C) is a sectional view taken along the X-X line and Y-Y line in each (a), and FIG. 7 is an electric circuit diagram as shown on a monitor. Figure 8 is a characteristic diagram corresponding to Figure 3, @ Figures 9 to 11 show general thin film magnetic heads, and Figure 9 (a)
and (b) are plan views and cross-sectional views, and FIGS.
(b)) is a cross-sectional view of the forming process, Figure 11 is a cross-sectional view after completion, @12 Figures (a) and (b) are a plan view and cross-sectional view of a conventional depth control monitor, and Figure @13 is a cross-sectional view of the conventional depth control monitor. A plan view of another conventional monitor, FIG. 14, is a characteristic diagram corresponding to FIG. 3 of the monitor shown in FIG. @13. ! 1) ...Ferromagnetic substrate, (2a), (2b) -@
1, second insulating layer, (3) ... conductor layer, C4),
,, upper magnetic layer, (5a), (5b)... through hole, (6) t (6)... gap forming layer, α9°O6... depth control monitor, αQ, αη... Conductor layer, (g), Ql... through hole, (2o),
(2oa), (2ob) --- Conductive magnetic layer.

Claims (1)

[Claims] (1) forming a conductor layer on the lower magnetic core via a first insulating layer, forming a second insulating layer covering the conductor layer, and forming a through hole in both the insulating layers to determine the depth end;
In the thin-film magnetic head, an upper magnetic core is formed on the lower magnetic core of the through hole to face the lower magnetic core via a gap forming layer, and the conductor layer is linked to a magnetic loop formed by both the magnetic cores. conductive magnetic material that electrically connects the two conductor patterns through two conductor patterns formed on the core and through holes on the conductor patterns formed in both the insulating layers when the through holes are formed; A thin film magnetic head characterized by being equipped with a depth control monitor consisting of a layer.